Starting vehicle engine, engine coolant temperature < 60 °C and outdoor air temperature ≤ 5 °C

P83.70-0323-09

1 Burner housing

2 Heat exchanger

A6m2 Combustion air blower

S25/17 ECT switch

S25/18 Air temperature switch

Y23 Stationary heater fuel metering pump

A6n1 Stationary heater/heater booster control module

A6r2 Glow pin

G2 Generator

M13 Coolant circulation pump

Operation

1 Coolant temperature < 60 °C
Outdoor temperature  5 °C
The switching contacts in the engine coolant temperature switch (S25/17) and air temperature switch (S25/18) are closed. Electronic control module (A6n1) is ready for starting up the heater booster.

2 The vehicle engine is started. The coolant circulation pump (M13) pumps coolant through the heat exchanger (2). The switching contacts in the two temperature switches connected in series are closed connecting positive voltage from the generator (G2), circuit 61 (charge indicator) to the control module (A6n1).

3 The positive signal causes the control module to start up the heater booster. The combustion air blower (A6m2) runs at nearly full load speed.

-----------------------------------------------------------------------------------------

4 The flame monitor check is started for 2 s, the glow pin (A6r2) provides a flame monitor function reporting:

 "COLD" = no flame present  start-up operation is continued.

 "HOT" = flame present  start-up is terminated due to defective glow pin (malfunction switch-off).

5 The glow pin is switched on. The preglowing time of approx. 40 s starts.

6 After completion of the preglowing time, the combustion air blower (A6m2) is switched off for 3 s and the fuel metering pump (Y23) starts supplying fuel.

7 The combustion air blower (A6m2) starts up again. The speed increases during the next 60 s to the medium speed range. The fuel metering pump (Y23) pumps at its lowest capacity. The fuel and combustion air form the fuel/air mixture in the burner housing (1).

-----------------------------------------------------------------------------------------

8 After 60 s a stabilization time of approx. 15 s starts for flame formation. The combustion air blower continues to blow air in constantly at medium speed during this time.

9 After completion of the stabilization time the combustion air blower and fuel metering pump increase speed and output during the next 50 s to nearly full load operation.

10 After increase in the combustion air and fuel quantity has been completed, the glow pin is switched off and the safety time of approx. 45 s for flame monitoring starts:

 The glow pin takes over the function of the flame monitor for checking the flame.

11 After completion of the safety time the glow pin indicates:

 "HOT" = sufficient flame formation  heating operation is continued.

 "COLD" = no flame present or flame formation insufficient  the fuel metering pump (Y23) is switched off and the start-up operation is repeated once.

12 After stabilization of the combustion the combustion air blower and fuel metering pump operate at maximum speed and output. The heat is exchanged in the heat exchanger (2) and the coolant temperature increases.